Models and drawings created by Advance Steel can't be opened in pure Autocad without at least an AS viewer license.
But, we can explode both the model the created drawings to simple, Autocad elements which will then be accessible to Autocad, even on systems that doesn't have Advance Steel installed.
For the 3D model, there is an FAQ describing the steps you need to do in order to export it : http://www.graitec.com/en/FAQ_view.asp?FAQID=555&Language=EN.
Drawing files can be exported from the Document Manager, using the Batch explode functionality. The drawing files are exploded in a dedicated folder, while the original files (AS files) are kept untouched. More information about this explode can be found in the on-line documentation : http://www.graitec.info/Common/Downloads/Documentation/AS-UserGuide-2010-EN-metric.pdf at page 153.